The water cycle and tides
GeographyWater & OceansAges 11–12
Use it with your class: students open it from a link or a QR code, with no account needed.
Next in Water & Oceans
An animated sea–mountain scene: seawater evaporates under the Sun's heat (evaporation speeds up as temperature rises), water vapour rises and drifts with the wind, condenses into clouds, falls as rain on the mountains, then returns to the sea through surface runoff and groundwater. Count the number of water droplets at each stage. The small panel on the right shows the Moon (draggable) pulling on the seawater to create tides, with sea level in the scene rising and falling on a cycle of about 12 hours 25 minutes.
Lesson: The hydrosphere and the water cycle; seas and oceans (tides)
What it shows
The water cycle is a closed loop driven by energy from the Sun and by gravity. Solar heating evaporates seawater; the rising vapour cools and condenses into cloud droplets, wind carries the clouds inland, and air forced up over the mountains cools further until the water falls as rain. Gravity then returns it to the sea as surface runoff in rivers or, more slowly, as groundwater. In the model the evaporation rate rises steadily with sea surface temperature, and droplet counters let students track water through each stage. A second panel links tides to the Moon's gravitational pull, which raises two bulges of water on opposite sides of Earth.
How to use
Start with Show stage names on and press Run to follow droplets through each stage, then turn the names off and ask students to identify the stages themselves. Compare a cool sea (5 °C) with a warm one (35 °C) using Sea surface temperature and watch the evaporation counter. Set Onshore wind speed to 0 and then to 10 to see how quickly clouds reach the mountains. With Show tide model on, drag the Moon and watch where the water rises.
Parameters you can change
- Sea surface temperature 5–40 °C
- Onshore wind speed 0–10 m/s
- Simulation speed 0.2–3 hours/second
- Show stage names
- Show tide model
Questions to explore
- Which stages carry water from the land back to the sea, and which of them is slower?
- How does the number of evaporated droplets change when the sea surface temperature rises from 10 °C to 35 °C?
- Why does most of the rain in the model fall over the mountains rather than over the sea?
